Influence of different pin profiles on the evaluation of interfacial microstructure and mechanical properties of Ti/Al by FSW process

This study employs friction stir welding to join dissimilar aluminium and titanium alloys using various pin profiles: straight cylindrical, threaded tapered cylindrical, straight hexagon, tapered hexagon, and straight threaded cylindrical. Welding parameters include rotational speeds of 250-450 rpm, 35 mm/min welding speed, and 3 mm axial feed. SEM analysis reveals defect-free welds at the Ti/Al interface with the straight hexagon tool at higher rotational speeds. XRD confirms brittle α-phase TiAl and ductile β-phase TiAl3 intermetallic compounds (IMCs) at the interface. Maximum micro hardness occurs near the stir zone due to IMC formation using the straight hexagon tool at 350 rpm. This sustainable, low-energy welding process enhances resource efficiency and promotes sustainable industrialisation by enabling lightweight, durable hybrid structures for aerospace and automotive applications, reducing material waste and fossil fuel dependency.